Castings of aluminum alloys



= UNITED STATES PAT ENI OFFlCE I also; 1 i casriisosorfammim ai mrsiaulmoieties, Bitterte a, I to L G."Farbenindustrie Aktiengesellacha!Frankiort-on-the-Main, Germany. v

No Drawing. Original application April 24, 1935 Serial No. 17,971.Divided and this application January 27, 1937, Serial No. 122,565; l n'Ger- The present invention relates to castings made manganese, isheated to about 300 (7., its tensile I of aluminumalioys, which castingshave acomstrength is only about 25% lower thaniat room pact texture anda'high mechanical strength at temperature, whereas, in the case ofthesame elevated temperatures. alloy, containing only 0.2%.01 silicon,the strength I This application is a division oi my applicaat 300.C3is:already more than 35% lower; 6

tion Serial No. 17,97l filed April 24, 1935, and en- This observationprobably aiiords at least a'} titled Castings of aluminium alloysfhpartial explanation of the more compact texture It has been found thataluminum castings of a of the castings made from the siliceous alloys,compact texture and a hifihmechanical strength since, owing to thegreater. strength of these al- 10 at elevated temperatures are obtainedbyusing l0,ys at the higher temperatures through which 10 an aluminumalloy containing ofirom about 3%; they pass after solidification, theloosening of to about 16% of magnesium and from about 0.8 theirstructure is correspondingly siighter.

to about 3% of silicon and which may further- Castings made of thefollowing aluminum al- 1 more' contain manganese to about 2.5%. The loysshow the describedequalities: 1 amount of added silicon depends on andvaries directly with the magnesium .contentof the alloy, er cent v thehigher the magnesium content,- the larger Mg being theamount of siliconneeded to produce M o2 the desired-effect.- On the other-benaiiowever, 7a

80 higherperce'ntages of silicon result in a consider- (3) Mg ,5.0 (4)-Mg 5.0 so;

, able lowering of the strength and elongation o1 Mn 0.3 Mn 0.3

the alloys, sothat, in" order to obtaincastings' s1 1.5 .si 3.0

which will meet the usual commercial require ments in this respect, theaddition of silicon to 28 alloys high in magnesium must remainbelo'w'the optimum amounts forthe attainment of compact texture; Bearingthese conditions in mind, alloys 1 t8 t h that have been iound-suitableare those-contain- I i ifi g t t 1 ing between-about5 and about'7% ofniagnesiuint res o e r 5: 5: ness 0 80 and between'about-ofi and*1 5% ofsilicon (the m m conjunc w e r own Prop- 50 latter increasing withinthe'spe'cifl'edlimits, with -P t -S cmfrosmn' h alloys of W pres thmagnesium c t ge-51 alloy) V v I sent invention arejsultable fortheproduction of a suitable alloy is one containingi5% ot.niagnesiuin igreat variety o vmould castings, such as'fittings and 1 to 1.2%or'siiieoneamang anese, i amounts .i x p co veyi q s, a bu et er p ts,86 upto 2.5% (preferably i abcu t.i1%-) inaylalso be hydraulic'controlmembers, mpressor casings, incorporated with the alloy. i I :vesselsforcontaining liquids'and gases, and the It has also been. observed thatthe'alloys conlikeJ tainlng,-. silicon in the amounts. above specified 1l are notably superior, in' respect also of their Castings of ammim malloys consisting of about Evencastin'gs with comparatively'thin walls"(for example about 5 mm.) made from alloys in 5 accordance with theinvention, are practically quite impervious undera positive pressure ofat to th at high temp ratu st p d- 5 to 7% of magnesium, about 0.8 to1.5% ofsilii alloys containingeitherv no si n at or con,'-the balancebeing' aluminum, and the quans c am o silicon, tnotmore than about tityof silicon increasing as the quantityof mac'- 0.3%, as are normally presn 8 imp s- 'nesium increases within the respective rangesmuch. [a hf ps, the t e specified, such castings having a compact texture strength oft 3 imin shesto-a less extent and a high mechanical strength at elevatedtem-' than that of the. corresponding alloys free from peratu'res.

' silicon. For examp1et-wlin an'alloy containing Pain. sPnALE -t 5% ofmagnesium, 1.1% ofasilicon and 0.1%01?

